1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same. Particularly, the present invention relates to: a semiconductor device including a metal ribbon for connecting an electrode of a semiconductor element and a lead together; and a method of manufacturing the same.
2. Description of the Related Art
Descriptions will be provided for a conventional semiconductor device 100 while referring to FIGS. 9A and 9B. FIG. 9A is a plan view of the semiconductor device 100, and FIG. 9B is a plan view showing a part of a manufacturing process.
Referring to FIG. 9A, the conventional semiconductor device 100 includes: an island 101; a semiconductor element 103 fixedly bonded to the top surface of the island 101; leads 102; and a metal ribbon 105 for connecting the semiconductor element 103 and some of the leads 102 together. In addition, these components are integrally covered with a sealing resin, which is not illustrated.
An electrode 104 is provided on a principal surface of the semiconductor element 103. An end of the metal ribbon 105 is fixedly bonded to the electrode 104 by ultrasonic bonding. The other end of the metal ribbon 105 is fixedly bonded to the leads 102. Thereby, the electrode 104 of the semiconductor element 103 and the leads 102 are electrically connected to each other.
Referring to FIG. 9B, through the manufacturing process of the semiconductor device 100, an individually-diced semiconductor element 103 is fixedly bonded to the top of the island 101 of a lead frame 110, as well as the electrode 104 and the leads 102 are electrically connected to each other by a bonder.
In other words, once the metal ribbon 105 is ultrasonic-bonded to the electrode 104, a capillary supporting the metal ribbon 105 is moved toward the leads 102 to connect the metal ribbon 105 and the leads 102 together. The term “capillary” means a tool that supplies a metal ribbon. During this time, the metal ribbon 105 is fixedly bonded to the leads 102 with the leads 102 and hanging pins 115, which connect the lead frame 110 and the island 101 together, pressed down respectively by dampers 120 of the bonder, in order to prevent the island 101 from being lifted up as a result of the metal ribbon 105 being pulled by the movement of the capillary (see Japanese Patent Application Publication No. 2008-294384, for example).
The metal ribbon 105 is larger in size and harder than a metal thin wire. For this reason, when the capillary is moved toward the leads 102 after ultrasonic-bonding the metal ribbon 105 to the electrode 104, the metal ribbon 105 is pulled in conjunction with the movement, and the already-fixed island 101 is accordingly lifted up.
When the island 101 is lifted up, some problems occur. The problems include: deformation of the lead frame 110; and the impossibility of forming a bonding loop of the metal ribbon 105 in an appropriate shape although the bonding loop of the metal ribbon 105 is expected to be formed in an arch shape to prevent the semiconductor element 103 and the metal ribbon 105 from contacting each other.
In order to prevent the island 101 from being lifted up, the hanging pins 115, which are integrated with the island 101, needs to be clamped by use of the dampers 120 of the bonder (as shown in FIG. 9B). Otherwise, the island 101 needs to be directly clamped in a way that its marginal portion (peripheral area) T situated outside its portion where the semiconductor element 103 is placed is clamped by use of the dampers 120 of the bonder.
However, hanging pins 115 are not provided to all the lead frames 110. The hanging pins 115 are provided particularly in a case where the corresponding semiconductor elements 103 have a larger chip size to keep the degree of balance during the manufacturing process. On the other hand, as is often the case with semiconductor elements 103 for which the degree of balance does not matter because of, for example, their smaller chip size, no hanging pins 115 are provided to the corresponding lead frames 110 with the influence of the hanging pins on the moisture resistance and the like taken into consideration, because the hanging pins 115 are led out of the sealing resin and the like after a product completion.
In addition, because the size of the island 101 and the size of the semiconductor 103 become close to each other in response to the miniaturization of (the package size of) the semiconductor device 100, it is impossible to secure the peripheral area T of the island 101, which is large enough to be clamped by the dampers 120, in an area outside the semiconductor element 103.
A technique of drawing the back surface of the island 101 by vacuum suction for the purpose of preventing the island 101 from being lifted up may be conceived as an idea. However, in a case where the semiconductor device 100 (the island 101) is smaller in size, it is impossible to form holes for vacuum suction in the placement surface of the bonder, on which the island 101 is placed. Furthermore, even if the holes could be formed there, the suction force is insufficient because the area drawn by suction is too small, and it is accordingly impossible to prevent the island 101 from being lifted up.